So you got a map email from Valve? A complete guide on what to do next

So you got an email from Valve about your map getting in the next update! First of all, congrats! You worked hard to get this far.
This guide is intended to help you on your way to deliver the map to Valve with as few headaches as possible by providing you an exhaustive list of everything you'll need to send them. It is now your job to make this process as easy as possible for Valve and to communicate everything clearly and in a timely fashion.